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Sejam os números x, y, z dados por: x = rac{1}{2} + rac{1}{6} + rac{1}{12} + rac{1}{20} + ext{...} + rac{1}{2019^2 - 2019} y = rac{1}{2} + rac{1}{6} + rac{1}{12} + rac{1}{20} + ext{...} + rac{1}{2019^2 - 2019} z = rac{1}{2} + rac{1}{6} + rac{1}{12} + rac{1}{20} + ext{...} + rac{1}{2019^2 - 2019}
O valor de ext{(x - rac{y}{2})^2 + rac{z}{3} é igual a:}